Site problems Test and Evaluation (T&E) The fundamental purpose of T&E is to provide knowledge to assist in the management of the risks involved in the development, production, operation and sustainment of a system and its capabilities. T&E is the process by which a system or components are compared against requirements and specifications through testing. The results are evaluated to assess progress of the design, performance, supportability etc. Developmental T&E is an engineering tool used to reduce risk throughout the defense acquisition cycle. Operational T&E is the actual or simulated employment of a system under realistic operational conditions. Defense Acquisition Guidebook (T&E)